Capacitor to be incorporated in wiring substrate, method for manufacturing the capacitor, and wiring substrate

ABSTRACT

A wiring substrate in which a capacitor is provided, the capacitor comprising a capacitor body including a plurality of dielectric layers and internal electrode layers provided between the different dielectric layers, wherein said capacitor body has, in at least one side face of said capacitor body, recesses extending in a thickness direction of said capacitor body from at least one of a first principal face of said capacitor body and a second principal face positioned on the side opposite to the first principal face.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a capacitor to be incorporated in awiring substrate, a method for manufacturing the capacitor, and thewiring substrate.

2. Description of the Related Art

In accordance with the progress of an integrated circuit technology ofrecent years, the actions of a semiconductor chip becomes higher andhigher in speeds. Accordingly, noises may be superposed on power sourcelines or the like to cause malfunctions. Thus, the noises are removed bymounting a capacitor on the upper face or lower face of a wiringsubstrate to mount the semiconductor chip.

In the aforementioned method, however, after completion of the wiringsubstrate, it is necessary to mount the capacitor separately, so thatthe process number increases. It is also necessary to retain such anarea in advance as to mount the capacitor on the wiring substrate, sothat the degree of freedom for other electronic parts is lowered. Due tothe restrictions by other wires, the wiring distance between thecapacitor and the semiconductor chip is elongated to increase the wiringresistance or inductance.

With these in mind, it has been proposed (as referred toJP-A-2005-39243, for example) to incorporate the capacitor in the wiringsubstrate. Here, the capacitor may be incorporated in the opening of acore substrate forming the core of the wiring substrate. In this case,the gap between the core substrate and the capacitor is filled with aresin filler so as to fix the capacitor in the core substrate. Since,however, the side faces of the capacitor are made mainly from ceramics,the adhesion properties between the capacitor and the resin filler areso low that the reliability cannot be sufficiently retained.

Moreover, a thermal stress is concentrated either in the resin fillerbetween the core substrate in the wiring substrate and the capacitor orin the insulating layers near the capacitor in the wiring substrate bythe heat which is generated at the action time of the semiconductorchip. As a result, cracks may be caused in the resin filler or theinsulating layers.

Against these problems, it has been proposed (as referred toJP-A-2004-172305, for example) to form rounded portions having a radiusof curvature of 0.01 to 0.1 mm between the side faces and the upper andlower faces of the capacitor. Since, however, the rounded portions areformed by a polishing method after the capacitor was sintered, thedielectric layers after sintered are worked to require long working timeperiods and high costs.

The capacitor to be incorporated in the wiring substrate, as describedin JP-A-2005-39243, is manufactured by forming a laminate including aplurality of dielectric layers laminated and internal electrode layersarranged between the dielectric layers, and by sintering the laminate.However, a warpage may occur at the sintering time. Therefore, it hasbeen proposed to prepare an assembly of the capacitor and to divide theassembly into capacitors after sintered.

Here in the capacitor to be incorporated in the wiring substrate, it isnecessary to form external electrode layers to be electrically connectedwith the wiring lines formed on the wiring substrate. On these externalelectrode layers, there may be formed plated external electrode layersfor improving the adhesion properties with the insulating layers of thebuildup layers, and plated films for preventing the oxidation of theexternal electrode layers. These plated films are formed at present byan electroless plating method.

However, it takes a long time to form the plated films by theelectroless plating method. In case the distance between the externalelectrode layers is so short as 150 μm, the external electrode layersmay be connected by the plated films and may be electrically shorted.

Thus, it has been proposed to form the plated films not by theelectroless plating method but by an electrolytic plating method. Incase, however, the aforementioned capacitor assembly is to bemanufactured, the break trenches for dividing the capacitor have to beformed in the assembly. Between the adjoining capacitors, therefore, theexternal electrode layers are spaced from each other across the breaktrenches. When the plated films are to be formed by the electrolyticplating method, therefore, the electrodes or the like have to be broughtinto contact for every external electrode layers so that the platedfilms cannot be efficiently formed by the electrolytic plating method.

There has been disclosed a technique (e.g., JP-A-61-276396), in whichthe boundaries between the body having the wiring pattern and a disposalplate are perforated, and in which the wiring pattern iselectrolytically plated. However, the perforations in this technique arejust for dividing the body and the disposal plate and have no relationto the electrolytic plating method.

3. Problems to be Solved by the Invention

The present invention has been proposed to solve the aforementionedproblems. Specifically, the invention has an object to provide acapacitor to be incorporated in a wiring substrate and capable ofimproving the adhesion properties with the wiring substrate, a wiringsubstrate having a reliability sufficiently retained, a capacitormanufacturing method capable of shortening the working time and reducingthe working cost for forming notched holes, a capacitor suited to beincorporated in the wiring substrate, a method for manufacturing thecapacitor to be incorporated in the wiring substrate and for formingplated films efficiently on external electrode layers by an electrolyticplating method, and a capacitor suited for incorporating the wiringsubstrate.

SUMMARY OF THE INVENTION

According to one mode of the invention, there is provided a wiringsubstrate incorporating a capacitor comprising a capacitor bodyincluding a plurality of dielectric layers and internal electrode layersarranged between the different dielectric layers. The wiring substrateis characterized in that the capacitor body has, in at least one sideface, recesses extending in the thickness direction (the direction fromthe first principal face to the second principal face, or the directionfrom the second principal face to the first principal face) of thecapacitor body from at least one of a first principal face of thecapacitor body and a second principal face positioned on the sideopposite to the first principal face.

According to a second mode of the invention, the wiring substrate ischaracterized by incorporating the capacitor to be incorporated therein.

According to the capacitor to be incorporated in the wiring substrate inaccordance with one mode of the invention, the recesses extending in thethickness direction of the capacitor body from at least one principalface are formed in at least one of the side faces of the capacitor body.When the capacitor is to be incorporated in the actual wiring substrate,the contact area with the resin material for being adhered to fix thecore substrate is enlarged by filling the resin material into therecesses. As a result, it is possible to improve the adhesion propertiesto the core substrate. Therefore, it is retain the reliability of thewiring substrate sufficiently in the second mode of the invention.

According to a third mode of the invention, there is provided a methodfor manufacturing a capacitor including a plurality of dielectric layersand a plurality of internal electrode layers arranged between thedifferent ones of the dielectric layers. The method is characterized bycomprising: the step of forming an unsintered laminate including aplurality of ceramic green sheets laminated to become the dielectriclayers, and a plurality internal electrode patterns arranged between thedifferent ones of the ceramic green sheets and adapted to become theinternal electrode layers; the step of forming notched holes in theouter periphery of such a portion in the laminate as to become thecapacitor; and the step of sintering the laminate having the notchedholes formed.

According to a fourth mode of the invention, there is provided acapacitor comprising a plurality of dielectric layers, and a pluralityof internal electrode layers arranged between the different ones of thedielectric layers. The capacitor is characterized: in that eitherchamfered portions having a chamfer dimension of 0.6 mm or more androunded portions having a radius of curvature of 0.6 mm or more areformed in at least one corner portion of the outer periphery of thecapacitor; in that the capacitor has a warpage of less than 100 μm; andin that the dielectric layers in the chamfered portions or the roundedportions have chipping quantities of 0.5 mm or less in their length,width and depth.

According to the capacitor manufacturing method of the third mode of theinvention, the notched holes are formed in the outer periphery of theportion to become the capacitor in the laminate before sintered, it ispossible to shorten the working time period at the time of forming thenotched holes and to lower the working the cost. According to thecapacitor of the fourth mode of the invention, it is possible to providea capacitor suited to be incorporated in the wiring substrate.

According to a fifth mode of the invention, there is provided a methodfor manufacturing a capacitor to be incorporated in a wiring substrateand comprising a capacitor body including a plurality of dielectriclayers and a plurality of internal electrode layers arranged between thedifferent ones of the dielectric layers, and external electrode layersformed on the capacitor body. The method is characterized by comprising:the step of forming a laminate including a plurality of ceramic greensheets containing a plurality of capacitor forming areas, which are tobe sintered to become the dielectric layers, and a plurality of internalelectrode patterns arranged in the individual ones of the capacitorforming areas and between the different ones of the ceramic greensheets, which are to be sintered to become the internal electrodelayers; the step of forming external electrode patterns extending on thelaminate and across two or more of the capacitor forming areas, andelectrically connected with the internal electrode patterns in theindividual ones of the capacitor forming areas, which are to be sinteredto become the external electrode layers; the step of forming first breaktrenches extending through the external electrode patterns, in thelaminate having the external electrode patterns formed, and extendingalong at least portions of the boundary of the individual ones of thecapacitor forming areas; the step of sintering the laminate having theexternal electrode patterns formed, after the first break trenches wereformed; the step of forming plated films electrolytically on theexternal electrode layers, after the laminate having the externalelectrode patterns formed was sintered, by feeding an electric currentto the external electrode layers; and the step of dividing the laminatehaving the plated films formed on the external electrode layers, alongthe first break trenches.

According to a sixth mode of the invention, there is provided acapacitor to be incorporated in a wiring substrate, comprising: acapacitor body including a plurality of dielectric layers, firstinternal electrode layers arranged between the dielectric layers, andsecond internal electrode layers provided so that the first internalelectrode layers and the second internal electrode layers arealternately arranged in the laminated direction of the dielectric layersthrough the dielectric layers; first external electrode layers formed onthe capacitor body and electrically connected with the first internalelectrode layers; second external electrode layers formed on thecapacitor body and substantially flush with (in substantially same planeas) the first external electrode layers, spaced from the first externalelectrode layers, and electrically connected with the second internalelectrode layers; and plated films electrolytically formed on the firstexternal electrode layers and the second external electrode layers. Thecapacitor is characterized: in that the capacitor has a warpage of lessthan 100 μm; and in that the plated films formed on the first externalelectrode layers and the plated films formed on the second externalelectrode layers are spaced at portions, in which the distance betweenthe first external electrode layers and the second external electrodelayers is 30 to 300 μm.

According to the fifth mode of the invention, the perforated first breaktrenches extending through the external electrode layers are formed inthe laminate having the external electrode layers formed. Therefore, itis possible to provide a method for manufacturing the capacitor to beincorporated in the wiring substrate, which method can form the platedfilms efficiently on the external electrode layers by the electrolyticplating method.

According to the sixth mode of the invention, the warpage of thecapacitor to be incorporated in the wiring substrate is less than 100μm, and the first plated films and the second plated films are spaced atportions where the distance between the first external electrode layersand the second external electrode layers are spaced at the distance of30 to 300 μm. Therefore, it is possible to provide a capacitor to beincorporated in the wiring substrate, which is suited to be incorporatedin the wiring substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A and FIG. 1B are schematic top plan views of a capacitor to beincorporated in a wiring substrate in accordance with first, fifth andseventh embodiments.

FIG. 2A and FIG. 2B are schematic side elevations of the capacitor to beincorporated in the wiring substrate in accordance with the first, fifthand seventh embodiment.

FIG. 3A is a schematic longitudinal section of the capacitor to beincorporated in the wiring substrate, when cut along line A-A of FIG.1A, and FIG. 3B is a schematic longitudinal section of the capacitor tobe incorporated in the wiring substrate, when cut along line B-B in FIG.1A.

FIG. 4 is enlarged schematic view of the vicinity of the outer peripheryof a capacitor body according to the first, fifth and seventhembodiments.

FIG. 5A and FIG. 5B are schematic top plan views of ceramic green sheetshaving internal electrode patterns formed according to the first, fifthand seventh embodiments.

FIG. 6A and FIG. 6B are schematic longitudinal sections of a laminateaccording to the first, fifth and seventh embodiments.

FIG. 7A is a schematic top plan view of a laminate according to thefirst, fifth and seventh embodiments, and FIG. 7B is a schematiclongitudinal section of the laminate according to the first, fifth andseventh embodiments.

FIG. 8A is a schematic top plan view of a laminate according to thefirst, fifth and seventh embodiments, and FIG. 8B is a schematiclongitudinal section of the laminate according to the first, fifth andseventh embodiments.

FIG. 9A is a schematic top plan view of a laminate according to thefirst, fifth and seventh embodiments, and FIG. 9B is a schematiclongitudinal section of the laminate according to the first, fifth andseventh embodiments.

FIG. 10A is a schematic top plan view of a laminate according to thefirst, fifth and seventh embodiments, and FIG. 10B is a schematiclongitudinal section of the laminate according to the first, fifth andseventh embodiments.

FIG. 11 is a schematic top plan view of a laminate according to thefirst, fifth and seventh embodiments.

FIG. 12A is a schematic top plan view of a laminate according to amodification of the first, fifth and seventh embodiments, and FIG. 12Bis a schematic longitudinal section of the laminate according to themodification of the first, fifth and seventh embodiments.

FIG. 13A is a schematic view showing the perforated break trenches, astaken from the surface side, after the laminate was cut into thecapacitor in the aforementioned modification, and FIG. 13B is aschematic view showing the perforated break trenches, as taken from theback side, after the laminate was cut into the capacitor in theaforementioned modification.

FIG. 14A is a schematic top plan view of a laminate according to anothermodification of the first, fifth and seventh embodiments, and FIG. 14Bis a schematic longitudinal section of the laminate according to anothermodification of the first embodiment.

FIG. 15 is a schematic view showing the perforated break trenches, astaken from the surface side, after the laminate was cut into thecapacitor in the aforementioned modification.

FIG. 16 is a schematic longitudinal section of the wiring substrate, inwhich the capacitor according to the first, fifth and seventhembodiments is incorporated.

FIG. 17A and FIG. 17B are schematic side elevations of a capacitor to beincorporated in the wiring substrate according to a second embodiment.

FIG. 18 is a schematic longitudinal section of the capacitor to beincorporated in the wiring substrate in accordance with the secondembodiment.

FIG. 19A and FIG. 19B are schematic side elevations of the capacitor tobe incorporated in the wiring substrate in accordance with a thirdembodiment.

FIG. 20 is a schematic longitudinal section of the wiring substrate, inwhich a capacitor to be incorporated in the wiring substrate inaccordance with fourth, sixth and eighth embodiments is incorporated.

FIG. 21A and FIG. 21B are schematic top plan views of another capacitorto be incorporated in the wiring substrate in accordance with the fifthembodiment.

FIG. 22A is a schematic top plan view of a laminate according to thefifth embodiment, and FIG. 22B is a schematic top plan view of anotherlaminate according to the fifth embodiment.

FIG. 23 is a schematic transverse section of the wiring substrate, inwhich the capacitor according to the fifth embodiment is incorporated.

FIG. 24 is an enlarged schematic view of the vicinity of the externalelectrode layer according to the seventh embodiment.

FIG. 25A and FIG. 25B are schematic top plan views of the laminateaccording to the seventh embodiment.

FIG. 26 is a schematic longitudinal section of the laminate according tothe seventh embodiment.

FIG. 27 is a schematic top plan view of the laminate according to theseventh embodiment.

FIG. 28A and FIG. 28B are schematic top plan views of the laminateaccording to the seventh embodiment.

FIG. 29 is a schematic top plan view of the laminate according to theseventh embodiment.

FIG. 30 is a schematic view showing the behavior at the time when thelaminate according to the seventh embodiment is divided.

DETAILED DESCRIPTION OF THE INVENTION First Embodiment

A first embodiment of the invention is described in the following withreference to the accompanying drawings. FIG. 1A and FIG. 1B areschematic top plan views of a capacitor to be incorporated in a wiringsubstrate in accordance with the embodiment, and FIG. 2A and FIG. 2B areschematic side elevations of the capacitor to be incorporated in thewiring substrate in accordance with the embodiment. FIG. 3A is aschematic longitudinal section of the capacitor to be incorporated inthe wiring substrate, when cut along line A-A of FIG. 1A; FIG. 3B is aschematic longitudinal section of the capacitor to be incorporated inthe wiring substrate, when cut along line B-B of FIG. 1A; and FIG. 4 isenlarged schematic view of the vicinity of the outer periphery of acapacitor body according to the embodiment.

A capacitor 1 to be incorporated in the wiring substrate (as will beshortly called the “capacitor”), as shown in FIG. 1A to FIG. 3B, is alaminated capacitor formed into a rectangular parallelepiped shape andhaving a warpage less than 100 μm. The capacitor 1 has a capacitor body2 forming the core of the capacitor 1. The capacitor body 2 isconstituted to include a plurality of dielectric layers 3 laminated inthe vertical direction, and a plurality of internal electrode layers 4(i.e., first internal electrode layers) and a plurality of internalelectrode layers 5 (i.e., second internal electrode layers) arrangedbetween the dielectric layers 3.

The dielectric layers 3 are made from dielectric ceramics such as bariumtitanate, lead titanate and strontium titanate. The dielectric layers 3can also be made from low-temperature sintered ceramics such as glassceramics prepared by adding an inorganic ceramic filler such as aluminato borosilicate glass or lead borosilicate glass, or high-temperaturesintered ceramics such as alumina, aluminum nitride, boron nitride,silicon carbide and silicon nitride, in accordance with the requiredcharacteristics.

The internal electrode layers 4 and 5 are alternately arranged in thelaminating direction of the dielectric layers 3 through the dielectriclayers 3. The internal electrode layers 4 and the internal electrodelayers 5 are electrically insulated from each other by the dielectriclayers 3. The total number of the internal electrode layers 4 and 5 isabout 100.

The internal electrode layers 4 and 5 are made mainly from a conductivematerial such as Ni, and contain a ceramic material like that making thedielectric layers 3. The adhesion properties between the dielectriclayers 3 and the internal electrode layers 4 and 5 can be enhanced bycontaining those ceramic materials individually in the internalelectrode layers 4 and 5. Here, the internal electrode layers 4 and 5need not contain such ceramic material. The internal electrode layers 4and 5 have a thickness of 2 μm or less.

The appearance of the capacitor body 2 is constituted to include a firstprincipal face 2 a positioned in the thickness direction of thecapacitor body 2, a second principal face 2 b positioned on the sideopposite to the first principal face 2 a, and an outer periphery 2 cpositioned between the first principal face 2 a and the second principalface 2 b. The outer periphery 2 c is composed mainly of a first sideface 2 c 1, a second side face 2 c 2 positioned on the side opposite(opposed) to the side face 2 c 1, a third side face 2 c 3 adjacent tothe side face 2 c 1 and the side face 2 c 2, and a fourth side face 2 c4 positioned on the side opposite (opposed) to the side face 2 c 3 andadjacent to the side face 2 c 1 and the side face 2 c 2. The side faces2 c 1, 2 c 2, 2 c 3 and 2 c 4 are made exclusively of the dielectriclayers 3. Here, the side faces of later-described recesses 2 d andnotches 2 e in the side faces 2 c 1, 2 c 2 and 2 c 3 are also madeexclusively of the dielectric layers 3.

Individually in the side faces 2 c 1, 2 c 2 and 2 c 3, as shown in FIG.2A and FIG. 2B, there are formed the semicylindrical recesses 2 dextending in the thickness direction of the capacitor body 2, and thenotches 2 e extending in the outer peripheral direction of the capacitorbody 2. In the side faces 2 c 1, 2 c 2 and 2 c 3, there may be formedridges extending in the thickness direction of the capacitor body 2 inplace of or together with the recesses 2 d. Moreover, the recesses 2 dand the notches 2 e may also be formed in the side face 2 c 4.

The recesses 2 d are formed in plurality at a predetermined gap alongthe outer periphery of the capacitor body 2. It is desired that therecesses 2 d in the side faces 2 c 1 and 2 c 2 are formed from the firstprincipal face 2 a to positions of 20% or more and 70% or less of thethickness of the capacitor body 2, and that the recesses 2 d in the sideface 2 c 3 are formed from the second principal face 2 b to positions of20% or more and 70% or less of the thickness of the capacitor body 2.These ranges are desired because the range of 20% or more can improvethe adhesion properties sufficiently with the later-described resinfiller 42 and because the range of 70% or less can reduce the crackingor chipping of the recesses 2 d, for example, at the time the capacitor1 is transported.

The recesses 2 d shown in FIG. 4 are desired to have a radius of 30 to75 μm. This is because the resin filler 42 cannot sufficiently flow, ifless than 30 μm, to make the adhesion properties insufficient or tolower the reliability with cavities, and because the area of theinternal electrodes becomes insufficient, if more than 75 μm, to causeshortage of the capacity. Moreover, the recesses 2 d need not besemicylindrical. The notches 2 e is formed from one end edge to theother of each of the side faces 2 c 1, 2 c 2 and 2 c 3. For example, thenotch 2 e of the side face 2 c 3 is formed from the end edge on the sideof the side face 2 c 1 to the end edge on the side of the side face 2 c2. In other words, the notches 2 e are formed to extend in the direction(outer peripheral direction) of the end edge of the side of the sideface 2 c 2 from the end edge of the side of the side face 2 c 1.

Moreover, it is preferred that the distance d1 between the recesses 2 d,as shown in FIG. 4, is more than 0 μm and less than 500 μm. This isbecause the plated film explained below cannot be formed in case thedistance d1 is 0 μm, and it may be difficult to divide the laminate 29for each of the capacitor forming areas R in case the distance d1 is 500μm or more.

In the side face 2 c 1, as shown in FIG. 2A, the recesses 2 d are formedin the side of the first principal face 2 a (extended in the thicknessdirection from the first principal face 2 a), and the notches 2 e areformed in the side of the second principal face 2 b. The side face 2 c 2is similar to the side face 2 c 1, although not shown. In the side face2 c 2, the recesses 2 d are formed in the side of the second principalface 2 b (extended in the thickness direction from the second principalface 2 b), and the notches 2 e are formed in the side of the firstprincipal face 2 a.

At the four corner portions of the outer periphery 2 c of the capacitorbody 2, as shown in FIG. 1A, there are formed flat-shaped chamferedportions 2 f having a chamfer dimension C1 of 0.6 mm or more. Thechamfer dimension C1 is a length shown in FIG. 1A. The chamfer dimensionC1 may be actually measured, but could be determined from a C facelength C2. This C face length C2 is the length of a segment, as shown inFIG. 1A, and the chamfer dimension C1 is the value obtained by dividingthe C face length C2 by √{square root over (2)}.

It is desired from the viewpoint of the capacitor manufacture that thechamfer dimension C1 is 0.8 mm or more and 1.2 mm or less. Here, a roundportion having a radius of curvature of 0.6 mm or more may be formed inplace of or together with the chamfered portions 2 f on at least onecorner of the outer periphery 2 c of the capacitor body 2. In this case,it is desired from the viewpoint of the capacitor manufacture that theradius of curvature of the rounded portion is 0.8 mm or more and 1.2 mmor less.

In the capacitor body 2, there are formed a plurality of via conductors6 (first via conductors) and a plurality of via conductors 7 (second viaconductors), which extend through the capacitor body 2 from the firstprincipal face 2 a to the second principal face 2 b. Here, the viaconductors 6 and 7 may extend through at least one dielectric layer 3 inthe thickness direction of the dielectric layers 3 but need not alwaysextend through the capacitor body 2.

The via conductors 6 are connected at their side faces with the internalelectrode layers 4, and the via conductors 7 are connected at their sidefaces with the internal electrode layers 5. In the internal electrodelayers 5, as shown in FIG. 3A, gap holes 5 a (hole portions) are formedat areas, through which the via conductors 6 extend. The internalelectrode layers 5 and the via conductors 6 are electrically insulatedfrom each other. Likewise, as shown in FIG. 3B, gap holes 4 a (holeportions) are formed at areas, through which the via conductors 7extend. The internal electrode layers 4 and the via conductors 7 areelectrically insulated from each other. Here, the dielectric layers 3are interposed between the internal electrode layers 4 and 5 and the viaconductors 6 and 7 in the gap holes 4 a and 5 a.

The via conductors 6 and 7 are made mainly from a conductive materialsuch as Ni and Cu, and contain a ceramic material similar to that makingthe dielectric layers 3. The adhesion properties of the dielectriclayers 3 and the via conductors 6 and 7 can be enhanced by containingsuch ceramic material individually in the via conductors 6 and 7. Here,the via conductors 6 and 7 may not contain such ceramic material.

On the first principal face 2 a and the second principal face 2 b, thereare individually formed external electrode layers 8 (first externalelectrode layers) and external electrode layers 9 (second externalelectrode layers), which are used as the power feeding terminals orground connecting terminals. Here, the external electrode layers 8 and 9need not be formed on both the first principal face 2 a and the secondprincipal face 2 b of the capacitor body 2, but may be formed on eitherthe first principal face 2 a or the second principal face 2 b.

On the side of the first principal face 2 a, as shown in FIG. 1A, theexternal electrode layer 8 is formed to enclose the island-shapedexternal electrode layers 9. On the side of the second principal face 2b, as shown in FIG. 1B, the external electrode layer 9 is formed toenclose the island-shaped external electrode layers 8.

The external electrode layer 8 is formed on the via conductors 6 and iselectrically connected with the via conductors 6. On the other hand, theexternal electrode layer 9 is formed on the via conductors 7 and iselectrically connected with the via conductors 7.

On either the side of the first principal face 2 a or the side of theprincipal face 2 b, the external electrode layers 8 and the externalelectrode layers 9 are spaced from each other and are electricallyinsulated from each other. The distance d2 between the externalelectrode layers 8 and the external electrode layers 9 is preferred tobe smaller if they retain the insulation, and is 150 μm at some portion.

On the side of the first principal face 2 a, the external electrodelayers 8 and 9 have a total surface area of 45% or more and 90% or lessof the area of the first principal face 2 a. On the side of the secondprincipal face 2 b, the external electrode layers 8 and 9 have a totalsurface area of 45% or more and 90% or less of the area of the secondprincipal face 2 b. By thus setting the total surface area of theexternal electrode layers 8 and 9 within that range with respect to thearea of the first principal face 2 a and the second principal face 2 b,the exposed area of the dielectric layers 3 in the first principal face2 a and the second principal face 2 b can be reduced. As a result, it ispossible to improve the adhesion properties between the capacitor 1 andthe later-described insulating layers 44 and 48 can be improved.

On the side of the first principal face 2 a, the external electrodelayer 8 is formed from the end of the side of the side face 2 c 1 to theend of the side of the side face 2 c 2. In the external electrode layer8, there are formed recesses 8 a, which communicate with the recesses 2d of the side faces 2 c 1 and 2 c 2. The recesses 8 a are made to havethe same radius as the radius r of the recesses 2 d and are madeconcentric to the recesses 2 d. On the side of the second principal face2 b, moreover, the external electrode layer 9 is formed from the end ofthe side of the side face 2 c 3 to the end of the side of the side face2 c 4. In the external electrode layer 9, there are formed recesses 9 a,which communicate with the recesses 2 d of the side face 2 c 3. Therecesses 9 a are made to have the same radius as the radius r of therecesses 2 d and are made concentric to the recesses 2 d.

On the side of the first principal face 2 a, the external electrodelayer 8 may be formed from the end of the side of the side face 2 c 3 tothe end of the side of the side face 2 c 4. In this case, the firstprincipal face 2 a can be flattened to improve the adhesion propertieswith the later-described insulating layers 44 and 48 and so on and toform stable via conductors 61 and 62 and so on. On the side of thesecond principal face 2 b, the external electrode layer 9 may also beformed from the end of the side of the side face 2 c 1 to the end of theside of the side face 2 c 2.

The external electrode layers 8 and 9 are made mainly from a conductivematerial such as Ni, and contain a ceramic material like that making thedielectric layers 3. The adhesion properties between the dielectriclayers 3 and the external electrode layers 8 and 9 can be enhanced bycontaining those ceramic materials individually in the externalelectrode layers 8 and 9. Here, the external electrode layers 8 and 9need not contain such ceramic material.

On the surfaces of the external electrode layers 8 and 9, there areformed first plated films (although not shown) for improving theadhesion properties with the later-described insulating layers 44 and 48and via conductors 61 and 62 and so on. The first plated films also havea function to prevent oxidations of the external electrode layers 8 and9. The first plated films are formed by an electrolytic plating method.Here, the first plated film may also be formed by an electroless platingmethod. It is preferred that the first plated film is made from aconductive material such as Au and Cu. It is further preferred forimproving the adhesion properties with the insulating layer 44 that theoutermost surface is made from Cu.

Between the external electrode layers 8 and 9 and the first plated film,there is formed a second plated film (although not shown) forsuppressing the reduction of the adhesion properties with the externalelectrode layers 8 and 9 and the first plated film. When the ceramicmaterial is contained in the external electrode layers 8 and 9, asdescribed above, the ceramic material may be exposed to the surfaces ofthe external electrode layers 8 and 9, thereby to lower the adhesionproperties between the external electrode layers 8 and 9 and the firstplated film. In order to the adhesion properties from being lowered, thesecond plated film is formed. This second plated film is formed by theelectrolytic plating method. Here, the second plated film may also beformed by the electroless plating method, if it is formed by the platingmethod.

It is preferred that the second plated film is made from the sameconductive material as the major component of the external electrodelayers 8 and 9. However, the second plated film need not be formed, incase the external electrode layers 8 and 9 containing a ceramic materialadded can be directly plated to have high adhesion properties.

The capacitor 1 can be manufactured by the following procedure, forexample. FIG. 5A and FIG. 5B are schematic top plan views of ceramicgreen sheets having internal electrode patterns formed according to theembodiment, and FIG. 6A, FIG. 6B, FIG. 7B, FIG. 8B, FIG. 9B and FIG. 10Bare schematic longitudinal sections of a laminate according to theembodiment. FIG. 7A, FIG. 8A, FIG. 9A, FIG. 10A and FIG. 11 areschematic top plan views of the laminate according to the embodiment.

At first, a plurality of ceramic green sheets 22 having an internalelectrode pattern 21 formed thereon, and ceramic green sheets 24 havingan internal electrode pattern 23 formed thereon (FIG. 5A and FIG. 5B).Here, the internal electrode patterns 21 and 23 are those before theinternal electrode layers 4 and 5 are sintered, and the ceramic greensheets 22 and 24 are those before the dielectric layers 3 are sintered.

The internal electrode patterns 21 and 23 are individually formed incapacitor forming areas R. The capacitor forming areas R form thecapacitor 1 and exist in plurality in the ceramic green sheets 22 and24. In the drawings, the capacitor forming areas R are designated bydouble-dotted lines. The internal electrode patterns 21 and 23 are madefrom a conductor paste, for example.

The internal electrode patterns 21 and 23 are formed in the capacitorforming areas R by the screen-printing method, for example. Moreover,the internal electrode patterns 21 and 23 have gap holes 21 a and 23 a(hole portions) to become gap holes 4 a and 5 a, after sintered.

There are also prepared two cover layers 25, as shown in FIG. 6A. Thecover layers 25 are formed by laminating a predetermined number ofdielectric layers not having the internal electrode patterns 21 and 23formed.

After the ceramic green sheets 22 and 24 and the cover layer 25 wereprepared, the ceramic green sheets 22 and the ceramic green sheets 24are alternately laminated on the cover layer 25, and another cover layer25 is further laminated. After this, these layers are pressurized toform a laminate 26 (FIG. 6A).

After this laminate 26 was formed, there are formed via holes, whichextend from a principal face 26 a to a principal face 26 b of thelaminate 26. A conductive paste is injected into the via holes to formvia conductor pastes 27 and 28 (FIG. 6B). Here, the via conductor pastes27 and 28 are those before the via conductors 6, 7 are sintered.

Next, over the laminate 26 having the via conductor pastes 27 and 28formed, the laminate 26 formed by a similar procedure is laid to providecommunication between the via conductor pastes 27 and between the viaconductor pastes 28, and these components are pressurized to form alaminate 29 (FIG. 7A and FIG. 7B).

After this, in a principal face 29 a of the laminate 29 and in aprincipal face 29 b on the side opposite to the principal face 29 a,respectively, there are formed by a screen printing method or the likeexternal electrode patterns 30, which are connected with the viaconductor pastes 27 in the capacitor forming areas R, and externalelectrode patterns 31 which are connected with the via conductor pastes28 in the capacitor forming areas R (FIG. 8A and FIG. 8B). Here, theexternal electrode patterns 30 and 31 are those before the externalelectrode layers 8 and 9 are sintered.

The external electrode patterns 30 on the side of the principal face 29a are formed across the capacitor forming areas R, and externalelectrode patterns 31 on the side of the principal face 29 b are formedacross the capacitor forming areas R. In this embodiment, the externalelectrode patterns 30 on the side of the principal face 29 a are formedacross the capacitor forming areas R arranged in the longitudinaldirection of the principal face 29 a, and the external electrodepatterns 31 on the side of the principal face 29 b are formed across thecapacitor forming areas R arranged in the transverse direction of theprincipal face 29 b.

After the external electrode patterns 30 and 31 were formed on theprincipal faces 29 a and 29 b, perforated break trenches 29 c (firstbreak trenches) and continuous line break trenches 29 d (second breaktrenches) extending through the external electrode patterns 30 and 31are individually formed by a laser beam or the like along the boundariesof the capacitor forming areas R (FIG. 9A and FIG. 9B).

On the side of the principal face 29 a, the break trenches 29 c areformed in the boundaries along the transverse direction of the principalface 29 a in the capacitor forming areas R, and the break trenches 29 dare formed in the boundary along the longitudinal direction of theprincipal face 29 a in the capacitor forming areas R.

On the side of the principal face 29 b, the break trenches 29 c areformed in the boundaries along the longitudinal direction of theprincipal face 29 b in the capacitor forming areas R, and the breaktrenches 29 d are formed in the boundary along the transverse directionof the principal face 29 b in the capacitor forming areas R.

As shown in FIG. 9B, the perforated break trenches 29 c can be set tohave a depth a, which is 20 to 70% of the entire thickness of theproduct. In this case, the continuous line break trenches 29 d can beset to have a depth b, as expressed by a/b=0.25 to 35. Specifically, thedepth b can be set at ratios, as shown in Table 1. In this embodiment,the depth a is set to 63% of the entire thickness of the product, andthe depth b of the continuous line break trenches 29 d are set to 25% ofthe entire thickness of the product.

TABLE 1 Values Taken by b at a = 20% 10% 20% 30% 50% 70% 80% a:b 2 10.67 0.4 0.29 0.25 at a = 70% 2% 5% 10% 15% 20% 30% a:b 35 14 7 4.67 3.52.3

The break trenches 29 d are so formed on the sides of the principalfaces 29 a and 29 b as to intersect the break trenches 29 c at rightangles. Here, the break trench 29 c formed on the side of the principalface 29 b is formed at positions corresponding to the break trenches 29d formed on the side of the principal face 29 a and along the breaktrenches 29 d formed on the side of the principal face 29 a. Moreover,the break trenches 29 d formed on the side of the principal face 29 bare at positions corresponding to the break trenches 29 c formed on theside of the principal face 29 b and along the break trenches 29 c formedon the side of the principal face 29 b.

After the break trenches 29 c and 29 d were formed in the laminate 29,hole portions 29 e extending in the thickness direction through thelaminate 29 and trenches 29 f extending in the thickness direction areformed in the corner portions of the capacitor forming areas R (FIG.10A). As a result, the portions to become the chamfered portions 2 f areformed in the laminate 29.

After the hole portions 29 e and the trenches 29 f were formed in thelaminate 29, the laminate 29 having the external electrode layers 8 and9 formed therein is degreased, and is sintered at a predeterminedtemperature for a predetermined time period. By this sintering, theinternal electrode patterns 21 and 23, the ceramic green sheets 22 and24, the via conductor pastes 27 and 28 and the external electrodepatterns 30 and 31 are sintered to form the internal electrode layers 4and 5, the dielectric layers 3, the via conductors 6 and 7 and theexternal electrode layers 8 and 9 (FIG. 10B).

After this, the oxide films formed on the surfaces of the externalelectrode layers 8 and 9 by the sintering is removed by a polishingmethod such as the jet blasting method. After this, an electric currentis fed to the external electrode layers 8 and 9 to form the first andsecond plated films on the external electrode layers 8 and 9 by theelectrolytic plating method. On the side of the principal face 29 a,there are formed the break trenches 29 c, which are perforated so thatthe external electrode layers 8 are electrically connected with eachother in the longitudinal direction of the principal face 29 a. As aresult, the electric current flows from the external electrode layers 8of the capacitor forming areas R, as positioned at one end of thelongitudinal direction of the principal face 29 a, to the externalelectrode layers 8 of the capacitor forming areas R, as positioned atthe other end, so that the first plated film or the like can be formedas a whole in the longitudinal direction of the principal face 29 a onthe external electrode layers 8 by the electrolytic plating method.Therefore, the first plated film or the like can be efficiently formedon the external electrode layers 8. A similar description can be made onthe side of the principal face 29 b. On the side of the principal face29 b, however, the electric current flows from the external electrodelayers 8 of the capacitor forming areas R, as positioned on one end ofthe transverse direction of the principal face 29 b, to the externalelectrode layers 8 of the capacitor forming areas R, as positioned onthe other end.

At last, the laminate 29 is divided along the break trenches 29 c and 29d for each of the capacitor forming areas R thereby to manufacture thecapacitor 1 or the like shown in FIG. 1 (FIG. 11). In the thicknessdirection of the laminate 29, the break trenches 29 d are formed atpositions corresponding to the break trenches 29 c. It is, however,desired that the laminate 29 is so divided that the portions near thebreak trenches 29 c is earlier cut away than the portions near the breaktrenches 29 d. This desire is caused by the following reason. Since theexternal electrode layers 8 and so on exist between the break trenches29 c, the external electrode layers 8 and so on near the break trenches29 c may not be cut along the break trenches 29 c if the portions nearthe break trenches 29 d are earlier cut away than the portions near thebreak trenches 29 c.

FIGS. 12A, 12B, 13A and 13B are diagrams showing a modification of theaforementioned method for manufacturing the capacitor 1. FIGS. 12A and12B and FIGS. 13A and 13B show only the step portions different fromthose of the manufacture method of the modification. Here, FIG. 12A is aschematic top plan view of a laminate according to this modification,and FIG. 12B is a schematic longitudinal section of the laminate.

In this embodiment, as shown in FIGS. 12A and 12B, the perforated breaktrenches 29 c (the first break trenches) and the continuous line breaktrenches 29 d (the second break trenches) are formed, like the abovedescription, at right angles to each other on the side of the principalface 29 a, and the break trenches 29 d are formed generally in parallelwith the break trenches 29 c on the back side of the laminate 29.Moreover, the break trenches 29 c are formed to extend in the thicknessdirection of the laminate 29.

Therefore, the break trenches 29 c exhibit, in case the capacitor 1 iscut along the break trenches 29 c and 29 d, for example, a generallysemicircular shape, as shown in FIG. 13A, on the surface side, but suchan arcuate shape, as shown in FIG. 13B, on the back side that the centerportions containing the diametrical portions of the generallysemicircular shape are chipped because the hole shapes of the breaktrenches 29 c are flattened by the break trenches 29 d.

In the manufacture method of this embodiment thus far described, thebreak trenches 29 c extend through the laminate 29, and the breaktrenches 29 d are formed along the break trenches 29 c in the back sideof the laminate. It is, therefore, possible to divide the laminate 29more easily for each of the capacitor forming areas R. Moreover, thelaminate 29 can be so easily divided that the portions near the breaktrenches 29 c can be separated earlier than the portions near the breaktrenches 29 d. It is, therefore, possible to eliminate such a fearcaused by the earlier separation of the portions near the break trenches29 d than the portions near the break trenches 29 c that the externalelectrode layers 8 and so on near the break trenches 29 c are not cutalong the break trenches 29 c.

FIGS. 14A, 14B and 15 are diagrams showing another modification of theaforementioned method for manufacturing the capacitor 1. FIGS. 14A and14B and FIG. 15 show only the step portions different from those of themanufacture method of the modification. Here, FIG. 14A is a schematictop plan view of a laminate according to this modification, and FIG. 14Bis a schematic longitudinal section of the laminate like before.

In this embodiment, as shown in FIGS. 14A and 14B, the perforated breaktrenches 29 c (or the first break trenches) and the continuous linebreak trenches 29 d (or the second break trenches) are formed at rightangles to each other on the side of the principal faces 29 a, and thebreak trenches 29 d are formed generally in parallel with the breaktrenches 29 c on the back side of the laminate 29. Moreover, the breaktrenches 29 c are formed to extend in the thickness direction of thelaminate 29. In this embodiment, moreover, the break trenches 29 c donot exist by themselves on the side of the principal face 29 a, but arepartially replaced by the additional line (or rectangular, specifically)break trenches 29 h.

Therefore, in case the capacitor 1 is formed by cutting the laminateshown in FIGS. 14A and 14B along the break trenches 29 c, 29 d and 29 h,the generally semicircular portions caused by the break trenches 29 cand the rectangular portions caused by the break trenches 29 d coexiston the side of the principal face 29 a, as shown in FIG. 15.

In the manufacture method of this embodiment thus far described, thebreak trenches 29 c extend through the laminate 29, and the breaktrenches 29 d are formed along the break trenches 29 c in the back sideof the laminate. On the side of the principal face 29 a, moreover, thebreak trenches 29 c are partially replaced by the line (or rectangular)break trenches 29 h like the break trenches 29 d. It is, therefore,possible to divide the laminate 29 more easily for each of the capacitorforming areas R. Moreover, the laminate 29 can be so easily divided thatthe portions near the break trenches 29 c can be separated earlier thanthe portions near the break trenches 29 d. It is, therefore, possible toeliminate such a fear caused by the earlier separation of the portionsnear the break trenches 29 d than the portions near the break trenches29 c that the external electrode layers 8 and so on near the breaktrenches 29 c are not cut along the break trenches 29 c.

The capacitor 1 is incorporated, when used, in the wiring substrate. Thewiring substrate having the incorporated capacitor 1 is described in thefollowing. FIG. 16 is a schematic longitudinal section of the wiringsubstrate, in which the capacitor according to this embodiment isincorporated.

A wiring substrate 40, as shown in FIG. 16, is an organic substrateformed into a rectangular parallelepiped shape. The wiring substrate 40is made mainly from a polymeric material, which is reinforced, forexample, by using ceramic particles or fibers as a filler.

The wiring substrate 40 is provided with a core substrate 41 as a wiringsubstrate body forming the core of the wiring substrate 40. The coresubstrate 41 is constituted to include a core member 41 a formed of aglass—epoxy resin composite material, for example, and wiring layers 41b of Cu or the like formed on the two faces of the core member 41 a andhaving a desired pattern.

In the core substrate 41, there are formed a plurality of through holes,which vertically extend through the core substrate 41. In the throughholes, there are formed through hole conductors 41 c, which areelectrically connected with the wiring layers 41 b.

In the central portion of the core substrate 41, there is formed anopening 41 d, for example, which acts as a capacitor housing portion foraccommodating the capacitor 1. The opening 41 d is formed into arectangular parallelepiped shape larger than the capacitor 1, andaccommodates the capacitor 1. Here, the capacitor housing portion of thecore substrate 41 should not be limited to the opening 41 d but may beexemplified by a recess.

At the four corner portions of the inner side face of the core substrate41, there are formed either the founded portion having a radius ofcurvature of 0.1 mm or more and 2 mm or less, or a chamfered portionhaving a chamfer dimension of 0.1 mm or more and 2 mm or less.

The gap between the core substrate 41 and the capacitor 1 is filled witha resin filler 42 made from a polymeric material or the like, forexample, as a filler. The capacitor 1 is fixed through that resin filler42 with respect to the core substrate 41. The resin filler 42 enters therecesses 2 d.

The gap between the core substrate 41 and the capacitor 1 is filled withthe resin filler 42, for example, such that the position of thecapacitor 1 is fixed by the adhesive tape with respect to the coresubstrate 41 by adhering an adhesive tape to the back of the coresubstrate 41 and by arranging the capacitor 1 in the opening 41 d of thecore substrate 41 so as to adhere the back of the capacitor 1 to theadhesive tape. Here, the resin filler 42 has an action to absorb thethermal expansion differences in the in-plane direction and in thethickness direction between the core substrate 41 and the capacitor 1 byits own elastic deformation.

Buildup wiring layers 43 are formed above the core substrate 41 and theprincipal face 1 a of the capacitor 1 and below the core substrate 41and the principal face 1 b of the capacitor 1. The buildup wiring layers43 are provided with insulating layers 44 to 50 made from a thermosetresin such as an epoxy resin. Between the insulating layers 44 and 45and so on, there are formed wiring layers 51 to 56, which are made froma conductive material such as Cu.

The upper face of the insulating layer 47 and the lower face of theinsulating layer 50 are covered with solder resists 57 and 58 made froma photosensitive resin composite or the like, for example. The solderresists 57 and 58 are provided with openings, from which a terminal 59to be electrically connected with the semiconductor chip (although notshown) and a terminal 60 to be electrically connected with a mainsubstrate (although not shown), for example, are exposed to the outside.The external electrode layers 8 and 9, the wiring layer 41 b and so onare electrically connected with the terminal 59 through the viaconductor 61 and so on, and the external electrode layers 8 and 9, thewiring layer 41 b and so on are electrically connected with the terminal60 through via the via conductor 62.

In this embodiment, the recesses 2 d extending in the thicknessdirection of the capacitor body 2 are formed in the side face 2 c 1 andso on so that they can also be filled with the resin filler 42 therebyto enlarge the contact area between the capacitor 1 and the resin filler42. Therefore, it is possible to improve the adhesion properties betweenthe resin filler 42 and the capacitor 1 and further to improve theadhesion properties between the resin filler 42 and the core substrate41. As a result, it is possible to ensure the fixture between the coresubstrate 41 and the capacitor 1 thereby to provide a highly reliablewiring substrate 40. Here, effects like the aforementioned ones can alsobe attained, even in case projections extending in the thicknessdirection of the capacitor body 2 are formed on the side face 2 c 1 andso on in place of or together with the recesses 2 d.

Moreover, the recesses 2 d can increase the filling quantity of theresin filler 42 the more as their number is the more within such a rangeas to deteriorate the strength of the capacitor 1. As a result, thefixture between the core substrate 41 and the capacitor 1 can be mademore reliable to provide the highly reliable wiring substrate 40.

In this embodiment, the recesses 2 d are formed in the side faces 2 c 1and 2 c 2 on the side of the first principal face 2 a, and the recesses2 d are formed in the side face 2 c 3 on the side of the secondprincipal face 2 b so that the vertical movements of the capacitor 1with respect to the core substrate 41 can be suppressed. In the statewhere the capacitor 1 is incorporated in the wiring substrate 40,specifically, the recesses 2 d are formed in the side faces 2 c 1 and 2c 2 on the side of the first principal face 2 a, and the resin filler 42has filled the recesses 2 d. Even in case, therefore, a force is appliedfrom the second principal face 2 b to the first principal face 2 a, itis hard to move the capacitor 1 upward. Moreover, the recesses 2 d areformed in the side face 2 c 3 on the side of the second principal face 2b, and the resin filler 42 has filled the recesses 2 d. Even in case,therefore, a force is applied from the first principal face 2 a to thesecond principal face 2 b, it is hard to move the capacitor 1 downward.Therefore, it is possible to suppress the vertical movements of thecapacitor 1 with respect to the core substrate 41.

Since the side face 2 c 1 and so on are made exclusively of thedielectric layers 3 as in this embodiment, the external electrode layers8 on the side of the first principal face 2 a and the external electrodelayers 9 on the side of the second principal face 2 b are hard to shortelectrically, even in case the shavings, as are discharged when thebreak trenches 29 c and 29 d are to be formed, of the external electrodepatterns 30 and 31 stick to the side face 2 c 1 and so on.

If the capacitor having a warpage of 100 μm or more is to beincorporated in the wiring substrate 40, it is difficult to incorporatethe capacitor in the wiring substrate 40, and it is liable that cracksare formed in the dielectric layers constituting the capacitor. In thisembodiment, on the contrary, the capacitor 1 has a warpage of less than100 μm, it is easy to incorporate the capacitor 1 in the wiringsubstrate 40, and the cracks are hard to form in the dielectric layers 3when the capacitor 1 is to be incorporated in the wiring substrate 40.

In this embodiment, the chamfered portions 2 f having the chamferdimension C1 of 0.6 mm or more are formed at the corner portions of theouter periphery 2 c of the capacitor body 2. As a result, the thermalstress is hard to concentrate at the corner portions of the resin filler42 on the side of the capacitor 1 so that the cracks can be preventedfrom occurring at the corner portions of the resin filler 42 on the sideof the capacitor 1. Here, effects like those of the chamfered portions 2f can also be attained, even in case rounded portions having a radius ofcurvature of 0.6 mm or more are formed at the corner portions of theouter periphery 2 c of the capacitor body 2.

In this embodiment, the chamfered portions 2 f and the rounded portionsare formed at the corner portions of the outer periphery 2 c of thecapacitor body 2. In case, therefore, neither the chamfered portions 2 fnor the rounded portions are formed, the distances from the signal linesexisting near the corner portions of the capacitor 1 to the dielectriclayers 3 are enlarged. Therefore, it is possible to reduce the signaldelays of the signal lines existing near the corner portions of thecapacitor 1.

There exists the so-called “castellation” for forming recesses in theend portions of the wiring substrate thereby to form the terminalelectrodes in those recesses. In the castellation, not the resinmaterial but the terminal electrodes are formed in the recesses. In themode of using the specific constitution and recesses, therefore, theinvention is different from the castellation.

Second Embodiment

A second embodiment of the invention is described with reference to theaccompanying drawings. This embodiment is described on the example, inwhich the capacitor body is provided with dummy electrodes closer to theside of the outer periphery of the dielectric layer than the internalelectrode layers. Here in the second to eighth embodiments, the sameportions as those having been described in the first embodiment aredesignated by the common reference numerals, and the contentsoverlapping those having been described in the first embodiment may beomitted. FIG. 17A and FIG. 17B are schematic side elevations of acapacitor to be incorporated in the wiring substrate according to thisembodiment. FIG. 18 is a schematic longitudinal section of the capacitorto be incorporated in the wiring substrate.

In the capacitor body 2, as shown in FIGS. 17A and 17B and FIG. 18,there are arranged dummy electrode layers 10 and 11, which do notfunction as electrodes. Specifically, the dummy electrode layers 10 and11 are arranged between the dielectric layers 3 at predetermined gapsfrom the internal electrode layers 4 and 5 on the side closer to theouter periphery (i.e., to the outer periphery 2 c) of the dielectriclayers 3 than the internal electrode layers 4 and 5.

The dummy electrode layers 10 (the first dummy electrode layers) arearranged in substantially the same plane as that of the internalelectrode layers 4, and the dummy electrode layers 11 (the second dummyelectrode layers) are arranged in substantially the same plane as thatof the internal electrode layers 5. Specifically, the dummy electrodelayers 10 are arranged between the same layers as those between thedielectric layers 3, in which the internal electrode layers 4 arearranged, and the dummy electrode layers 11 are arranged between thesame layers as those between the dielectric layers 3, in which theinternal electrode layers 5 are arranged. Here, the dummy electrodelayers 10 and 11 may also be formed between the layers different fromthose between the dielectric layers 3, in which the internal electrodelayers 4 and 5 are arranged.

The internal electrode layers 4 and the dummy electrode layers 10, andthe internal electrode layers 5 and the dummy electrode layers 11 areelectrically insulated from each other. Here, the dielectric layers 3individually enter gaps s1 and s2 between the internal electrode layers4 and 5 and the dummy electrode layers 10 and 11 thereby to insulate theinternal electrode layers 4 and 5 and the dummy electrode layers 10 and11 reliably electrically.

The gaps s1 between the internal electrode layers 4 and the dummyelectrode layers 10 and the gaps s2 between the internal electrodelayers 5 and the dummy electrode layers 11 have so positional relationsas are deviated in the thickness direction of the capacitor body 2 thatthey do not overlap. Here, the gaps s1 between the internal electrodelayers 4 and the dummy electrode layers 10 are arranged with each otherin the thickness direction of the capacitor body 2, and the gaps s2between the internal electrode layers 5 and the dummy electrode layers11 are arranged with each other in the thickness direction of thecapacitor body 2.

The dummy electrode layers 10 and 11 are formed to enclose the internalelectrode layers 4 and 5. Moreover, the outer peripheries 10 a and 11 aof the dummy electrode layers 10 and 11 are exposed from between thedielectric layers 3 to the outside. Therefore, the side faces 2 c 1, 2 c2, 2 c 3 and 2 c 4 are constituted of the dielectric layers 3 and thedummy electrode layers 10 and 11. Here, the side faces of the recesses 2d and the notches 2 e in the side faces 2 c 1, 2 c 2 and 2 c 3 are alsoconstituted of the dielectric layers 3 and the dummy electrode layers 10and 11.

Considering the reduction of the steps to be formed near the endportions of the capacitor 1, it is preferred that the outer peripheriesof the dummy electrode layers 10 and 11 are wholly exposed from betweenthe dielectric layers 3 to the outside, but it is arbitrary that theouter peripheries 10 a and 11 a are only partially exposed to theoutside.

Considering the reduction of the steps to be formed near the endportions of the capacitor 1, it is preferred that the total number ofthe dummy electrode layers 10 and 11 is one half (about fifty layers) ormore of that of the internal electrode layers 4 and 5, and it is morepreferred that the total number is substantially equal (about 100layers) to that of the internal electrode layers 4 and 5.

The dummy electrode layers 10 and 11 are made from a conductivematerial. Considering the influences at the sintering steps and theforming steps of the ceramic green sheets 22 and 24, however, it ispreferred that the conductive material to make the dummy electrodelayers 10 and 11 are the same conductive material as that to make theinternal electrode layers 4 and 5. For similar reasons, moreover, it ispreferred that the thickness of the dummy electrode layers 10 and 11 issubstantially equal to that (e.g., 2 μm or less) of the internalelectrode layers 4 and 5.

In this embodiment, too, the recesses 2 d extending in the thicknessdirection of the capacitor body 2 are formed in the side face 2 c 1 andso on, so that effects substantially similar to those of the firstembodiment can be attained. In this embodiment, like the firstembodiment, the projections extending in the thickness direction of thecapacitor body 2 may be formed in the side face 2 c 1 and so on in placeof or together with the recesses 2 d. In this case, too, effects similarto the aforementioned ones can be attained.

In this embodiment, the dummy electrode layers 10 and 11 are formed onthe side closer to the outer periphery of the dielectric layers 3 thanthe internal electrode layers 4 and 5. Therefore, the end portions ofthe capacitor body 2 can be made thick to provide the capacitor 1, inwhich the steps to be formed near the end portions thereof can bereduced. When the gaps between the core substrate 41 and the capacitor 1are filled with the resin filler 42, therefore, this resin filler 42 ishard to dive to the back side (the side of the second principal face 2b) of the capacitor 1. As a result, it is possible to reduce the faultsat the subsequent buildup step.

In case the gap s1 between the internal electrode layers 4 and the dummyelectrode layers 10 and the gap s2 between the internal electrode layers5 and the dummy electrode layers 11 overlap in the thickness directionof the capacitor body 2, there exist the portions, in which both theinternal electrode layers 4 and 5 and the dummy electrode layers 10 and11 are absent in the thickness direction of the capacitor body 2. Theseportions have neither the internal electrode layers 4 and 5 and thedummy electrode layers 10 and 11 so that they become thinner than theremaining portions and are locally recessed. In case these recesses areformed at portions relatively near the outer periphery of the capacitor1, the resin filler 42 may dive to the back side of the capacitor 1. Inthis embodiment, on the contrary, the gap s1 between the internalelectrode layers 4 and the dummy electrode layers 10 and the gap s2between the internal electrode layers 5 and the dummy electrode layers11 do not overlap in the laminating direction of the dielectric layers3. Therefore, such local recesses is hardly formed to suppress the diveof the resin filler 42.

In this second embodiment, the dummy electrode layers 10 and 11 may alsobe replaced by at least either the internal electrode layers 4 or 5,which extend to the side faces 2 c 1, 2 c 2, 2 c 3 and 2 c 4 of thecapacitor body 2. In case the internal electrode layers 4 and 5 areexposed to the side faces 2 c 1, 2 c 2, 2 c 3 and 2 c 4 and in case theshavings of the external electrode patterns 30 and 31 stick to the sidefaces 2 c 1, 2 c 2, 2 c 3 and 2 c 4, the end portions of the capacitorbody 2 can be easily made thick, although shorts may occur. As a result,the steps to be formed near the end portions of the capacitor 1 can bereduced. In case the shavings stick to the side faces 2 c 1, 2 c 2, 2 c3 and 2 c 4, it is also possible to add the step of removing theshavings and so on.

Third Embodiment

A third embodiment of the invention is described in the following withreference to the drawings. This embodiment is described on the example,in which recesses extending from one principal face to the otherprincipal face are formed in the side faces of the capacitor body. FIG.19A and FIG. 19B are schematic side elevations of the capacitor to beincorporated in the wiring substrate in accordance with this embodiment.

As shown in FIG. 19A and FIG. 19B, the recesses 2 d provided in the sidefaces 2 c 1, 2 c 2 and 2 c 3 are formed from the first principal face 2a to the second principal face 2 b of the capacitor body 2. In the sidefaces 2 c 1, 2 c 2 and 2 c 3, moreover, projections extending from thefirst principal face 2 a to the second principal face 2 b of thecapacitor body 2 may also be formed in place of or together with therecesses 2 d. In this embodiment, the notches 2 e are not formed. Inthis embodiment, moreover, the dummy electrode layers 10 and 11 are notarranged, but may also be arranged.

In this embodiment, too, the recesses 2 d extending from the firstprincipal face 2 a to the second principal face 2 b of the capacitorbody 2 are formed in the side face 2 c 1 and so on, so that similareffects as those of the first embodiment can be attained. Here, effectssimilar to the aforementioned ones can also be attained, in case theprojections extending from the first principal face 2 a to the secondprincipal face 2 b of the capacitor body 2 are formed in the side face 2c 1 and so on in place of or together with the recesses 2 d.

Fourth Embodiment

A fourth embodiment of the invention is described in the following withreference to the drawing. This embodiment is described on the example,in which the capacitor is arranged between the insulating layers on thecore substrate. FIG. 20 is a schematic longitudinal section of thewiring substrate 40′, in which a capacitor to be incorporated in thewiring substrate in accordance with this embodiment is incorporated.

As shown in FIG. 20, no opening is formed in the core substrate 41, butthe capacitor 1′ is arranged between the insulating layers 44 and 45above the core substrate 41. The capacitor 1′ of this embodiment has atotal number of ten of the internal electrode layers 4 and 5, and isthinner than the capacitor 1, which has been described in connectionwith the first embodiment.

The capacitor 1′ can be arranged between the insulating layers 44 and45, for example, by the following procedure. At first, the capacitorbody 2 having the plated films formed on the external electrode layers 8and 9 is arranged over the insulating layer 44 formed on the coresubstrate 41. After this, the insulating layer 45 is placed on thecapacitor body 2, and these components are pressurized while beingheated. As a result, the insulating layer 45 on the capacitor body 2flows sideway of the capacitor body 2 so that the capacitor body 2 isarranged between the insulating layers 44 and 45. After this, via holesare formed through the insulating layers 44 and 45, and the viaconductors 6 and 7 connected with the wiring layer 41 b are formed inthe via holes thereby to complete the capacitor 1′.

In this embodiment, the capacitor 1′ is arranged between the insulatinglayers 44 and 45 formed on the core substrate 41 so that the distancebetween the capacitor 1′ and the semiconductor chip can be made shorter.Therefore, it is possible to reduce the wiring resistance and theinductance.

Fifth Embodiment

A fifth embodiment of the invention is described in the following withreference to the accompanying drawings. FIG. 1A and FIG. 1B areschematic top plan views of a capacitor to be incorporated in a wiringsubstrate in accordance with the embodiment; FIG. 3A is a schematiclongitudinal section of the capacitor and taken along line A-A of FIG.1A; and FIG. 3B is a schematic longitudinal section of the capacitor andtaken along line B-B of FIG. 1A. FIG. 21A and FIG. 21B are schematic topplan views of another capacitor to be incorporated in the wiringsubstrate in accordance with this embodiment.

The capacitor 1 to be incorporated in the wiring substrate (as will beshortly called the “capacitor”), as shown in FIGS. 1A, 1B, 3A and 3B, isa laminated capacitor formed into a rectangular parallelepiped shape andhaving a warpage less than 100 μm. The capacitor 1 is preferred to havelongitudinal and transverse dimensions of 5.0 mm or more. The capacitor1 is formed to have those dimensions so that it can have similar size asthat of the semiconductor chip. Therefore, it is possible to effectivelyreduce the thermal expansion difference between the semiconductor chipand the wiring substrate 40.

In the side faces 2 c 1, 2 c 2 and 2 c 3 of the capacitor body 2, thereare individually formed the semicylindrical trenches 2 d extending inthe thickness direction of the capacitor body 2 and the trenches 2 eextending in the circumferential direction. In this embodiment, thetrenches 2 d and 2 e are formed by dividing the laminate 29 along thelater-described break trenches 29 c and 29 e. In this embodiment, thetrenches 2 d and 2 e are not formed but may also be formed in the sideface 2 c 4.

The chamfered portion 2 f may be formed in at least one corner portionof the outer periphery 2 c of the capacitor 1. Considering thesuppression of the cracks of the later-described resin filler 42 or thelike, however, it is preferred that the chamfered portions 2 f areformed in all the corner portions.

Of the four chamfered portions 2 f, only one chamfered portion 2 fhaving a different chamfer dimension C1 may be formed in the capacitor1. Moreover, only one chamfered portion 2 f need not be changed in thechamfer dimension C1 but may also be changed in the shape.

It is desired from the viewpoint of the manufacturing of the capacitorthat the chamfer dimension C1 is 0.8 mm or more and 1.2 mm or less. Asshown in FIG. 21A and FIG. 21B, moreover, a rounded portion 1 g having aradius of curvature R1 of 0.6 mm or more may be formed, in place of ortogether with the chamfered portions 2 f, in at least one corner portionof the outer periphery 2 c of the capacitor 1. In this case, it isdesired from the viewpoint of the capacitor manufacture that the radiusof curvature R1 of the rounded portion 1 g is 0.8 mm or more and 1.2 mmor less. As in the chamfered portions 2 f, moreover, only one of therounded portions 1 g may also be provided with a rounded portion 1 ghaving a radius of curvature R1 different from that of the remainingrounded portions 1 g.

The chipping quantity of the dielectric layers 3 of one chamferedportion 2 f or the rounded portion 1 g is desired to be 0.5 mm or lessfor the length, width and depth.

In the procedure of manufacturing the capacitor 1, as described inconnection with the first embodiment, after the break trenches 29 c and29 d were formed in the laminate 29, the hole portions 29 e extending inthe thickness direction of the laminate 29 and trenches 29 f extendingin the thickness direction are formed (FIG. 22A) in the outer peripheryof a portion 290 to become the capacitor 1, that is, in portions 29 a 1(the corner portion of the capacitor forming areas R) to become thecorner portions of the outer periphery 2 c of the capacitor 1 in theportion 290 to become the capacitor 1. The trenches 29 f are formed onthe outer periphery of the laminate 29. Chamfered portions 29 h (thenotched holes) to become the chamfered portions 2 f of the capacitor 1are formed in the laminate 29 by forming the hole portions 29 e and thetrenches 29 f. Rounded portions 29 i (notched holes) to become therounded portions 1 g of the capacitor 1 can also be formed (FIG. 22B) inplace of or together with the chamfered portions 29 h by a similarmethod in the laminate 29. The chamfered portions 29 h and the roundedportions 29 i are the portions to become the chamfered portions 2 f andthe rounded portions 1 g after the laminate 29 was divided. Here, thechamfer dimension of the chamfered portions 29 h is similar to thechamfer dimension C1 of the chamfered portions 2 f, and the radius ofcurvature of the rounded portions 29 i is similar to the radius ofcurvature R1 of the rounded portions 1 g.

The capacitor 1 is incorporated, when used, in the wiring substrate. Thewiring substrate having the incorporated capacitor 1 is described in thefollowing. FIG. 16 is a schematic longitudinal section of the wiringsubstrate, in which the capacitor according to this embodiment isincorporated, and FIG. 23 is a schematic transverse section of thewiring substrate, in which the capacitor according to this embodiment isincorporated. The description, which has been made on the firstembodiment in FIG. 16, is applied to this embodiment.

It is preferred that the core substrate 41 has an opening diameter d2 of13.0 mm or more and 15.0 mm or less. The opening diameter d2 is thelength of one side of the opening 41 d and is specified by the lengthshown in FIG. 23. The reason why the opening diameter d2 of the coresubstrate 41 is 13.0 mm or more is that the opening 41 d has to belarger than the size of the capacitor 1 so as to accommodate thecapacitor 1. In case either of the longitudinal or transverse dimensionis 13.0 mm, it is natural that the opening diameter d2 of the coresubstrate 41 is larger than 13.0 mm. The reason why the opening diameterd2 of the core substrate 41 is 15.0 mm or less is that the routing ofthe wiring in the wiring substrate 40 is difficult if the opening 41 dis excessively large.

The gap s, as shown in FIG. 23, between the core substrate 41 and thecapacitor 1 is preferred to be 0.5 mm or more and 2.0 mm or less,because it is difficult to fill the later-described resin filler 42, ifthe gap is excessively narrow, and because the wiring space of the coresubstrate 41 is short, if the cap is excessively wide.

As shown in FIG. 23, moreover, rounded portions 41 e having a radius ofcurvature R2 of 0.1 mm or more and 2 mm or less are formed in the fourcorner portions of the inner side face of the core substrate 41. Here,the rounded portions 41 e need not be formed, but may be formed, ifformed, in at least one portion of the inner side face of the coresubstrate 41. Chamfered portions having a chamfer dimension of 0.1 mm ormore and 2 mm or less may be formed in the corner portions of the innerside face in place of or together with the rounded portions 41 e.

In this embodiment, the chamfered portions 29 h or the rounded portions29 i are formed in the laminate 29 before sintered. Therefore, theceramic green sheets 22 and 24 or the like, which are so softer than thedielectric layers 3 as can be easily worked, are chamfered or rounded.As a result, it is possible to shorten the working time period at thetime of forming the chamfered portions or the rounded portions and toreduce the working cost.

In case the chamfered portions 29 h or the rounded portions 29 i areformed in the sintered laminate 29, the working precision is so poor aswill invite the chipping at the chamfering or rounding time. In thisembodiment, however, the chamfered portions 29 h or the rounded portions29 i are formed in the laminate 29 before sintered, so that the workingprecision can be improved. As a result, the chipping quantity of thedielectric layers 3 at the chamfering or rounding time can be reduced toreduce the dispersion among the products.

In this embodiment, the hole portions 29 e and the trenches 29 f can beformed in the laminate 29 to form the chamfered portions 29 h or therounded portions 29 i all at once.

The ceramic green sheets 22 and 24 and so on are softer than thedielectric layers 3 but are relatively hard. In case the chamferedportions 29 h or the rounded portions 29 i are formed by a punchingmethod, the ceramic green sheets 22 and 24 and so on may be chipped atthe chamfering or rounding time. In this embodiment, on the contrary,the chamfered portions 29 h or the rounded portions 29 i are formed witha laser beam so that the working precision can be better improved. As aresult, it is possible to reduce the chipping, as might otherwise becaused in the ceramic green sheets 22 and 24.

In case portions to become the capacitor 1 are individually sintered,the warpage of the capacitor 1 may become excessively large. In thisembodiment, on the contrary, the portions 290 to become the capacitor 1are sintered in the state of the laminate 29 composed of the portions290, so that the warpage of the capacitor 1 can be reduced.

In this embodiment, the chamfered portions 2 f having the chamferdimension C1 of 0.6 mm or more are formed in the corner portions of theouter periphery of the capacitor 1. As a result, the thermal stress ishard to concentrate at the corner portions of the resin filler 42 on theside of the capacitor 1 so that the cracks can be prevented fromoccurring at the corner portions of the resin filler 42 on the side ofthe capacitor 1. Here, effects like those of the chamfered portions 2 fcan also be attained, even in case rounded portions 1 g having a radiusof curvature of 0.6 mm or more are formed at the corner portions of theouter periphery 2 c of the capacitor 1.

In this embodiment, the chamfered portions 2 f and/or the roundedportions 1 g are formed at the corner portions of the outer periphery 2c of the capacitor 1. In case, therefore, neither the chamfered portionsnor the rounded portions are formed, the distances from the signal linesexisting near the corner portions of the capacitor 1 to the dielectriclayers 3 are enlarged. Therefore, it is possible to reduce the signaldelays of the signal lines existing near the corner portions of thecapacitor 1.

If the capacitor having a warpage of 100 μm or more is to beincorporated in the wiring substrate 40, it is difficult to incorporatethe capacitor in the wiring substrate 40, and it is liable that cracksare formed in the dielectric layers constituting the capacitor. In thisembodiment, on the contrary, the capacitor 1 has a warpage of less than100 μm, it is easy to incorporate the capacitor 1 in the wiringsubstrate 40, and the cracks are hard to form in the dielectric layers 3when the capacitor 1 is to be incorporated in the wiring substrate 40.

In this embodiment, the trenches 2 d are formed in the side faces 2 c 1,2 c 2 and 2 c 3 of the capacitor 1. Therefore, the resin filler 42enters the trenches 2 d when the capacitor 1 is incorporated in thewiring substrate 40. As a result, it is possible to improve the adhesionproperties between the capacitor 1 and the resin filler 42.

Sixth Embodiment

A sixth embodiment of the invention is described with reference to theaccompanying drawing. This embodiment is described on the example, inwhich the capacitor is arranged between the insulating layers on thecore substrate. Here in this embodiment, the same portions as thosehaving been described in the first and fifth embodiments are designatedby the common reference numerals, and the contents overlapping thosehaving been described in the first and fifth embodiments may be omitted.FIG. 20 is a schematic longitudinal section of a wiring substrate, inwhich a capacitor according to this embodiment is incorporated.

As shown in FIG. 20, no opening is formed in the core substrate 41, butthe capacitor 1″ is arranged between the insulating layers 44 and 45above the core substrate 41. The capacitor 1″ of this embodiment has atotal number of ten of the internal electrode layers 4 and 5, and isthinner than the capacitor 1, which has been described in connectionwith the fifth embodiment.

The capacitor 1″ can be arranged between the insulating layers 44 and45, for example, by the following procedure. At first, the capacitorbody 2 having the external electrode layers 8 and 9 formed thereon isarranged over the insulating layer 44 formed on the core substrate 41.After this, the insulating layer 45 is placed on the capacitor body 2,and these components are pressurized while being heated. As a result,the insulating layer 45 on the capacitor body 2 flows sideway of thecapacitor body 2 so that the capacitor body 2 is arranged between theinsulating layers 44 and 45. After this, via holes are formed throughthe insulating layers 44 and 45, and the via conductors 6 and 7connected with the wiring layer 41 b are formed in the via holes therebyto complete the capacitor 1″.

In this embodiment, the capacitor 1″ is arranged between the insulatinglayers 44 and 45 formed on the core substrate 41 so that the distancebetween the capacitor 1″ and the semiconductor chip can be made shorter.Therefore, it is possible to reduce the wiring resistance and theinductance.

Experiment Example

An experiment example of the invention is described in the following.This experiment example examined correlations between the chamferdimension of the chamfered portions at the corner portions of the outerperiphery of the capacitor and the cracks of the resin filler.

Experimental conditions are described. At first, there were prepared aplurality of core substrates, in which the opening diameters of thecapacitor housing portions in the core substrate and the radii ofcurvature of the rounded portions formed in the corner portions of theinner side face of the core substrate were different.

Specifically, there were prepared a plurality of core substrates, whichhad an opening diameter of 13.5 mm and a radius of curvature of 0.5 mm,which had an opening diameter of 13.5 mm and a radius of curvature of1.5 mm, which had an opening diameter of 14.0 mm and a radius ofcurvature of 0.5 mm, and which had an opening diameter of 14.0 mm and aradius of curvature of 1.5 mm. Moreover, capacitors having differentchamfer dimensions are housed in the openings of those core substrates,and a resin filler was filled between the core substrates and thecapacitors. The capacitors had longitudinal and transverse sizes of 12mm, and the chamfered portions of the capacitors were formed by cuttingthem with a cutter. It has been evaluated on the wiring substrateswhether or not cracks occurred in the resin fillers.

Experimental results are described.

TABLE 2 Core Core Substrate Substrate Chamfer c-Face Aperture Radius ofDimension Length Diameter Curvature (mm) (mm) Evaluation 13.5 mm 0.5 mm1.075 1.52 OK 0.940 1.33 OK 0.863 1.22 OK 0.841 1.19 OK 0.764 1.08 OK0.693 0.98 OK 0.622 0.88 OK 0.601 0.85 OK 0.559 0.79 OK 0.481 0.68 NG0.460 0.65 OK 0.453 0.64 OK 0.453 0.64 NG 0.424 0.60 NG 0.403 0.57 OK0.346 0.49 OK 13.5 mm 1.5 mm 1.174 1.66 OK 1.096 1.55 OK 0.933 1.32 OK0.856 1.21 OK 0.764 1.08 OK 0.679 0.96 OK 0.622 0.88 OK 0.615 0.87 OK0.594 0.84 OK 0.559 0.79 OK 0.509 0.72 NG 0.453 0.64 NG 0.389 0.55 NG0.382 0.54 OK 0.361 0.51 NG 0.332 0.47 NG

TABLE 3 Core Core Substrate Substrate Chamfer c-Face Aperture Radius ofDimension Length Diameter Curvature (mm) (mm) Evaluatino 14.0 mm 0.5 mm1.018 1.44 OK 0.933 1.32 OK 0.870 1.23 OK 0.820 1.16 OK 0.785 1.11 OK0.721 1.02 OK 0.608 0.86 OK 0.587 0.83 OK 0.502 0.71 OK 0.495 0.70 OK0.481 0.68 OK 0.474 0.67 NG 0.467 0.66 OK 0.460 0.65 NG 0.453 0.64 NG0.368 0.52 OK 14.0 mm 1.5 mm 1.153 1.63 OK 1.075 1.52 OK 0.983 1.39 OK0.905 1.28 OK 0.771 1.09 OK 0.770 0.99 OK 0.693 0.98 OK 0.665 0.94 OK0.622 0.88 OK 0.537 0.76 OK 0.502 0.71 OK 0.488 0.69 OK 0.417 0.59 NG0.389 0.55 OK 0.368 0.52 OK 0.311 0.44 NG

As shown in Table 2 and Table 3, cracks occurred in the resin filler incase the chamfered portions of the capacitor had the chamfer dimensionof 0.6 mm or less. In case the chamfered portions of the capacitor had achamfer dimension of 0.6 mm or more, no crack had occurred in all theresin fillers. From this result, it has been confirmed that theoccurrence of cracks in the resin filler could be suppressed in case thechamfered portions of a chamfer dimension of 0.6 mm or more were formedin the corner portions of the outer peripheries of the capacitors. Here,it is thought that similar effects can be attained in case the roundedportions of a radius of curvature of 0.6 mm or more are formed in thecorner portions of the outer peripheries of the capacitors.

The invention should not be limited to the described contents of theforegoing embodiments, but the structures or materials and thearrangements of the individual members could be suitably modifiedwithout departing from the gist of the invention. The foregoingembodiments have been described with the laminate 29 provided with theportions 290 to become the capacitor 1′, but the laminate 29 may beprovided with at least one portion 290 to become the capacitor 1′.Moreover, the notched holes have been described with the chamferedportions 29 h or the rounded portions 29 i, but the notches may be notonly the chamfered portions 29 h or the rounded portions 29 i but maytake any desired shape such as a polygonal shape other than therectangular shape. Even this case can acquire effects substantiallysimilar to those of the first and second embodiments.

Seventh Embodiment

A seventh embodiment of the invention is described in the following withreference to the accompanying drawings. FIG. 1A and FIG. 1B areschematic top plan views of a capacitor to be incorporated in a wiringsubstrate in accordance with the embodiment, and FIG. 2A and FIG. 2B areschematic side elevations of the capacitor to be incorporated in thewiring substrate in accordance with the embodiment. FIG. 3A is aschematic longitudinal section of the capacitor to be incorporated inthe wiring substrate, when cut along line A-A of FIG. 1A; FIG. 3B is aschematic longitudinal section of the capacitor to be incorporated inthe wiring substrate, when cut along line B-B of FIG. 1A; and FIG. 24 isan enlarged schematic view of the vicinity of the outer periphery of acapacitor body according to the embodiment.

A capacitor 1 to be incorporated in the wiring substrate (as will beshortly called the “capacitor”), as shown in FIG. 1A to FIG. 3B, is alaminated capacitor formed into a rectangular parallelepiped shape andhaving a warpage less than 100 μm. The capacitor 1 has a capacitor body2 forming the core of the capacitor 1. The capacitor body 2 isconstituted to include a plurality of dielectric layers 3 laminated inthe vertical direction, and a plurality of internal electrode layers 4(i.e., first internal electrode layers) and a plurality of internalelectrode layers 5 (i.e., second internal electrode layers) arrangedbetween the dielectric layers 3.

The external electrode layer 8 is formed on the via conductors 6 and iselectrically connected with the via conductors 6. On the other hand, theexternal electrode layer 9 is formed on the via conductors 7 and iselectrically connected with the via conductors 7.

On either the side of the first principal face 2 a or the side of theprincipal face 2 b, the external electrode layers 8 and the externalelectrode layers 9 are spaced from each other and are electricallyinsulated from each other. The distance d2 between the externalelectrode layers 8 and the external electrode layers 9 is 30 to 300 μmat some portion.

On the surfaces of the external electrode layers 8 and 9, as shown inFIG. 24, there is formed the plated films 100 for improving the adhesionproperties with the later-described insulating layers 44 and 48 and viaconductors 61 and 62 and so on. The plated films 100 also have afunction to prevent oxidations of the external electrode layers 8 and 9.The plated films 100 are formed by an electrolytic plating method. Theplated films 100 are made from an electrically conductive material suchas Au and Cu.

Between the external electrode layers 8 and 9 and the plated film 100,there is formed a plated film 110 for suppressing the reduction of theadhesion properties with the external electrode layers 8 and 9 and theplated film 100. When the ceramic material is contained in the externalelectrode layers 8 and 9, as described above, the ceramic material maybe exposed to the surfaces of the external electrode layers 8 and 9,thereby to lower the adhesion properties between the external electrodelayers 8 and 9 and the plated film 100. In order to the adhesionproperties from being lowered, the plated film 110 is formed. Thisplated film 110 is formed by the electrolytic plating method.

Individually in the side faces 2 c 1, 2 c 2 and 2 c 3, as shown in FIG.2A and FIG. 2B, there are formed the semicylindrical recesses 2 dextending in the thickness direction of the capacitor 1, and thetrenches 2 e extending in the outer peripheral direction of thecapacitor 1. In this embodiment, the trenches 2 d and 2 e are formed bydividing the laminate 29 along the later-described break trenches 29 cand 29 d. Here in this embodiment, the trenches 2 d and 2 e are notformed in the side face 2 c 4, but may also be formed in the side face 2c 4.

After the external electrode patterns 30 and 31 were formed on the firstprincipal face 29 a and the second principal face 29 b, perforated breaktrenches 29 c (first break trenches) and continuous line break trenches29 d (second break trenches) extending through the external electrodepatterns 30 and 31 are individually formed by a laser beam or the likealong the boundaries of the capacitor forming areas R (FIG. 25A, FIG.25B, FIG. 26 and FIG. 27).

On the side of the first principal face 29 a, the break trenches 29 care formed in the boundaries along the transverse direction of the firstprincipal face 29 a in the capacitor forming areas R, and the breaktrenches 29 d are formed in the boundary along the longitudinaldirection of the second principal face 29 b in the capacitor formingareas R.

On the side of the second principal face 29 b, the break trenches 29 care formed in the boundaries along the longitudinal direction of thesecond principal face 29 b in the capacitor forming areas R, and thebreak trenches 29 d are formed in the boundary along the transversedirection of the second principal face 29 b in the capacitor formingareas R.

The break trenches 29 d are so formed on the sides of the firstprincipal face 29 a and the second principal face 29 b as to intersectthe break trenches 29 c at right angles. Here, the break trench 29 cformed on the side of the second principal face 29 b is formed atpositions corresponding to the break trenches 29 d formed on the side ofthe first principal face 29 a and along the break trenches 29 d formedon the side of the first principal face 29 a. Moreover, the breaktrenches 29 d formed on the side of the second principal face 29 b areat positions corresponding to the break trenches 29 c formed on the sideof the first principal face 29 a and along the break trenches 29 cformed on the side of the first principal face 29 a.

The depth of the break trenches 29 c is desired to be 20% or more and70% or less of the thickness of the laminate 29. These ranges aredesired because the range of 20% or more allows the laminate 29 to beeasily divided along the break trenches 29 c, and because the range of70% or less can reduce the cracking or chipping of the break trenches 29c in the degreasing, sintering and transferring steps after the breaktrenches 29 c were formed.

In case the break trenches 29 c are cylindrical, the break trenches 29 care desired to have a radius r of 30 to 75 μm. This is because theplating liquid cannot be removed, in case it invades into the breaktrenches 29 c, by the subsequent rinsing operation, if less than 30 μm,and because the areas of the internal electrode layers 4 and 5 becomesinsufficient, to cause shortage of the capacity, if more than 75 μm.

It is preferred that the distance d3 between the break trenches 29 c ismore than 0 μm and less than 500 μm. This is because the plated filmexplained below cannot be formed in case the distance d3 is 0 μm, and itmay be difficult to divide the laminate 29 for each of the capacitorforming areas R in case the distance d3 is 500 μm or more.

After the break trenches 29 c and 29 d were formed in the laminate 29,the rectangular hole portions 29 e extending in the thickness directionof the laminate 29 are formed (as shown in FIG. 10A) along the boundaryof the corner portions of the capacitor forming areas R. The holeportions 29 e are formed to form the chamfered portions 2 f in thecapacitor 1. Here in this embodiment, the hole portions 29 e are formedafter the break trenches 29 c and 29 d were formed, but the breaktrenches 29 c and 29 d may also be formed after the hole portions 29 ewere formed.

After the hole portions 29 e were formed in the laminate 29, thelaminate 29 having the external electrode layers 8 and 9 formed thereinis degreased, and is sintered at a predetermined temperature for apredetermined time period. By this sintering, the internal electrodepatterns 21 and 23, the ceramic green sheets 22 and 24, the viaconductor pastes 27 and 28 and the external electrode patterns 30 and 31are sintered to form the internal electrode layers 4 and 5, thedielectric layers 3, the via conductors 6 and 7 and the externalelectrode layers 8 and 9 (FIG. 10B).

After this, the oxide films formed on the surfaces of the externalelectrode layers 8 and 9 by the sintering is removed by a polishingmethod such as the jet blasting method. After this, an electric currentis fed to the external electrode layers 8 and 9 to form the plated films100 and 110 on the external electrode layers 8 and 9 by the electrolyticplating method. On the side of the first principal face 29 a, there areformed the break trenches 29 c, which are perforated so that theexternal electrode layers 8 are electrically connected with each otherin the longitudinal direction of the first principal face 29 a. As aresult, the electric current flows (FIG. 25A) from the externalelectrode layers 8 of the capacitor forming areas R, as positioned atone end of the longitudinal direction of the first principal face 29 a,to the external electrode layers 8 of the capacitor forming areas R, aspositioned at the other end, so that the plated films 100 and 110 can beformed as a whole in the longitudinal direction of the first principalface 29 a on the external electrode layers 8 by the electrolytic platingmethod. As on the side of the second principal face 29 b, moreover, onthe side of the second principal face 29 b, the electric current flows(FIG. 28B) from the external electrode layers 8 of the capacitor formingareas R, as positioned at one end of the second principal face 29 b inthe transverse direction, to the external electrode layers 9 of thecapacitor forming areas R, as positioned on the other end. Here, arrowsin FIG. 28A and FIG. 28B indicate the directions, in which the electriccurrent flows.

At last, the laminate 29 is divided along the break trenches 29 c and 29d for each of the capacitor forming areas R thereby to manufacture thecapacitor 1 or the like shown in FIG. 1 (FIG. 29). In the thicknessdirection of the laminate 29, the break trenches 29 d are formed atpositions corresponding to the break trenches 29 c. It is, however,desired that the laminate 29 is so divided that the portions near thebreak trenches 29 c is earlier cut away than the portions near the breaktrenches 29 d (FIG. 30). This desire is caused by the following reason.Since the external electrode layers 8 and the plated films 100 and 110exist between the break trenches 29 c, the external electrode layers 8and the plated films 100 and 110 near the break trenches 29 c may not becut along the break trenches 29 c if the portions near the breaktrenches 29 d are earlier cut away than the portions near the breaktrenches 29 c.

Specifically, the portions near the break trenches 29 c on the side ofthe first principal face 29 a are so divided for every columns that theymay be cut away earlier than the portions near the break trenches 29 don the side of the second principal face 29 b, and the portions near thebreak trenches 29 c on the side of the second principal face 29 b are sodivided that they may be cut away earlier than the portions near thebreak trenches 29 d on the side of the first principal face 29 a.Incidentally, the portions near the break trenches 29 c on the side ofthe second principal face 29 b are so divided for every columns thatthey may be cut away earlier than the portions near the break trenches29 d on the side of the first principal face 29 a, and the portions nearthe break trenches 29 c on the side of the first principal face 29 a areso divided that they may be cut away earlier than the portions near thebreak trenches 29 d on the side of the second principal face 29 b.

The capacitor 1′″ is incorporated, when used, in the wiring substrate.The wiring substrate having the incorporated capacitor 1′″ is describedin the following. FIG. 16 is a schematic longitudinal section of thewiring substrate, in which the capacitor according to this embodiment isincorporated. The descriptions on the first embodiment with reference toFIG. 16 are also applied to those of this embodiment.

In this embodiment, on the side of the first principal face 29 a, theperforated break trenches 29 c extending through the external electrodelayers 8 are formed in the laminate 29, so that the external electrodelayers 8 are electrically connected with each other in the longitudinaldirection of the first principal face 29 a. As a result, the platedfilms 100 and 110 are formed as a whole by the electrolytic platingmethod in the longitudinal direction of the first principal face 29 a.Therefore, it is possible to form the plated films 100 and 110efficiently. Here, effects similar to the aforementioned ones can beattained because the break trenches 29 c are also formed on the side ofthe second principal face 29 b.

In this embodiment, the plated films 100 and 110 are formed by theelectrolytic plating method so that they can be precisely formed on theexternal electrode layers 8 and 9. Even in case, therefore, the distanced2 between the external electrode layers 8 and the external electrodelayers 9 is as narrow as 30 to 300 μm, the external electrode layers 8and the external electrode layers 9 are hard to connect through theplated films 100 and 110, so that the electric short can be suppressed.

In this embodiment, the plated films 100 and 110 can be preciselyseparated out, even if the distance d2 between the external electrodelayers 8 and the external electrode layers 9 is as relatively narrow as30 to 300 μm. Moreover, the plated films 100 and 110 can be plated inthe aggregate state of products, and the aggregate itself can behomogeneously plated as a whole.

In this embodiment, the trenches 2 d are formed in the side faces 2 c 1,2 c 2 and 2 c 3 of the capacitor 1′″. When the capacitor 1′″ isincorporated in the wiring substrate 40, the resin filler 42 enters thetrenches 2 d. It is, therefore, possible to improve the adhesionproperties between the capacitor 1′″ and the resin filler 42.

In this embodiment, the chamfered portions 2 f having the chamferdimension C1 of 0.6 mm or more are formed at the corner portions of theouter periphery 2 c of the capacitor body 2. As a result, the thermalstress is hard to concentrate at the corner portions of the resin filler42 on the side of the capacitor 1′″ so that the cracks can be preventedfrom occurring at the corner portions of the resin filler 42 on the sideof the capacitor 1′″. Here, effects like those of the chamfered portions2 f can also be attained, even in case rounded portions having a radiusof curvature of 0.6 mm or more are formed at the corner portions of theouter periphery 2 c of the capacitor body 2.

In this embodiment, the chamfered portions 2 f and the rounded portionsare formed at the corner portions of the outer periphery 2 c of thecapacitor body 2. In case, therefore, neither the chamfered portions 2 fnor the rounded portions are formed, the distances from the signal linesexisting near the corner portions of the capacitor 1′″ to the dielectriclayers 3 are enlarged. Therefore, it is possible to reduce the signaldelays of the signal lines existing near the corner portions of thecapacitor 1′″.

Eighth Embodiment

An eighth embodiment of the invention is described with reference to theaccompanying drawing. This embodiment is described on the example, inwhich the capacitor is arranged between the insulating layers on thecore substrate. Here in this embodiment, the same portions as thosehaving been described in the first and seventh embodiments aredesignated by the common reference numerals, and the contentsoverlapping those having been described in the first and seventhembodiments may be omitted. FIG. 20 is a schematic longitudinal sectionof a wiring substrate, in which a capacitor according to this embodimentis incorporated.

The invention should not be limited to the described contents of theforegoing embodiments, but the structures and materials and thearrangements of the individual members could be suitably modifiedwithout departing from the gist thereof.

This application is based on Japanese Patent Application JP 2005-370945,filed Dec. 22, 2005, Japanese Patent Application JP 2005-370946, filedDec. 22, 2005, and Japanese Patent Application JP 2005-370947, filedDec. 22, 2005, the entire contents of which are hereby incorporated byreference, the same as if set forth at length.

What is claimed is:
 1. A wiring substrate in which a capacitor isprovided, the capacitor comprising: a capacitor body including aplurality of dielectric layers laminated in a thickness direction andinternal electrode layers provided between different dielectric layers,wherein said capacitor body has, on at least one external side face ofsaid capacitor body, recesses extending in the thickness direction ofsaid capacitor body from at least one of a first principal face of saidcapacitor body and a second principal face positioned on a side oppositeto the first principal face, wherein the external side face extends fromthe first principal face to the second principal face and the recessesare formed on the external side face.
 2. The wiring substrate as claimedin claim 1, comprising a core substrate; wherein said capacitor is fixedto said core substrate through a resin material filling said recesses.3. The wiring substrate as claimed in claim 1, wherein at least one ofsaid first principal face and said second principal face of saidcapacitor body having said recesses formed therein has notches formedalong an outer periphery of said at least one of said first principalface and said second principal face.
 4. The wiring substrate as claimedin claim 1, wherein: said recesses are formed at least in a first sideface of said capacitor body and in a third side face adjacent to saidfirst side face; said recesses formed in said first side face are formedfrom said first principal face of said capacitor body; and said recessesformed in said third side face are formed from said second principalface of said capacitor body.
 5. The wiring substrate as claimed in claim4, wherein: said recesses are formed in a second side face opposite tosaid first side face and in a fourth side face opposite to said thirdside face; said recesses formed in said second side face are formed fromthe first principal face of said capacitor body; and said recessesformed in said fourth side face are formed from the second principalface of said capacitor body.
 6. The wiring substrate as claimed in claim1, wherein said recesses are formed from an end face side of at leastone of said first principal face and said second principal face of saidcapacitor body, to a position of from 20% to 70% less of the thicknessof said capacitor body.
 7. The wiring substrate as claimed in claim 1,wherein said recesses are formed to extend in a thickness direction ofsaid capacitor body from an end face of at least one of said firstprincipal face and said second principal face of said capacitor body. 8.The wiring substrate as claimed in claim 1, wherein said dielectriclayers includes ceramic, and said ceramic included in said dielectriclayers are exposed at a side face of said capacitor body in saidrecesses.
 9. The wiring substrate as claimed in claim 1, wherein pluralrecesses are formed at a spacing in the side face of said capacitorbody.
 10. The wiring substrate as claimed in claim 1, wherein saidcapacitor body further includes dummy electrode layers provided on aside closer to an outer periphery of said dielectric layers than saidinternal electrode layers and at a spacing from said internal electrodelayers.
 11. The wiring substrate as claimed in claim 1, wherein at leasta portion of said internal electrode layers is exposed at a side face ofsaid capacitor body.
 12. A method for manufacturing a wiring substrateincluding a capacitor comprising a capacitor body including a pluralityof dielectric layers laminated in a thickness direction and internalelectrode layers provided between different dielectric layers, whereinthe capacitor body has, on at least one external side face of thecapacitor body, recesses extending in the thickness direction of saidcapacitor body from at least one of a first principal face of saidcapacitor body and a second principal face positioned on a side oppositeto the first principal face, wherein the external side face extends fromthe first principal face to the second principal face and the recessesare formed on the external side face, the method comprising: forming anunsintered laminate including a plurality of ceramic green sheets tobecome said dielectric layers, and a plurality of internal electrodepatterns provided between different ceramic green sheets, said internalelectrode patterns to become said internal electrode layers; formingnotched holes in an outer periphery of a portion of said laminate whichis to become said capacitor; and sintering said laminate having saidnotched holes formed.
 13. The method as claimed in claim 12, whereinsaid forming of said notched holes is carried out by forming at leastone of hole portions extending in said laminate in a thickness directionof said laminate and trenches extending in an outer periphery of saidlaminate in said thickness direction.
 14. The method as claimed in claim12, wherein said forming of said notched holes is carried out with alaser.
 15. The method as claimed in claim 12, wherein said notched holesare at least one of chamfered portions and rounded portions.
 16. Themethod as claimed in claim 12, wherein: said laminate includes aplurality of said portions, each portion of which is to become one ofsaid capacitor; and the method further comprises dividing said laminate,after said sintering, into said portions, each of which is to become oneof said capacitor.
 17. A method for manufacturing a wiring substrateincluding a capacitor comprising a capacitor body including a pluralityof dielectric layers laminated in a thickness direction and internalelectrode layers provided between different dielectric layers, andexternal electrode layers provided on said capacitor body, wherein thecapacitor body has, on at least one external side face of the capacitorbody, recesses extending in the thickness direction of said capacitorbody from at least one of a first principal face of said capacitor bodyand a second principal face positioned on the a side opposite to thefirst principal face, wherein the external side face extends from thefirst principal face to the second principal face and the recesses aredisposed on the external side face, the method comprising: forming alaminate including: a plurality of ceramic green sheets containing aplurality of capacitor forming areas, which are to be sintered to becomesaid dielectric layers; and a plurality of internal electrode patternsprovided in individual capacitor forming areas and between differentceramic green sheets, which are to be sintered to become said internalelectrode layers; forming external electrode patterns extending on saidlaminate and across two or more of said capacitor forming areas, andelectrically connected with said internal electrode patterns in theindividual capacitor forming areas, which are to be sintered to becomesaid external electrode layers; forming first break trenches extendingthrough said external electrode patterns, in said laminate having saidexternal electrode patterns formed, and extending along at leastportions of a boundary of the individual capacitor forming areas;sintering said laminate having said external electrode patterns formed,after said first break trenches are formed; forming plated filmselectrolytically on said external electrode layers, after said laminatehaving said external electrode patterns formed is sintered, by feedingan electric current to said external electrode layers; and dividing saidlaminate having said plated films formed on said external electrodelayers, along said first break trenches.
 18. The method as claimed inclaim 17, wherein: said laminate has a first principal face positionedin a thickness direction of said laminate, and a second principal faceon the side opposite to said first principal face; and said externalelectrode layers are individually formed on said first principal faceand said second principal face of said laminate.
 19. The method asclaimed in claim 18, wherein: said first break trenches are formed inindividual portions on the side of said first principal face and on theside of said second principal face; and the method further comprises:forming, after said external electrode patterns are formed and beforesaid laminate having said external electrode patterns formed aresintered, second continuous line break trenches substantiallyperpendicular to said first break trenches, in portions of said laminateon the side of said first principal face and on the side of said secondprincipal face in said laminate along a portion of said boundaries; anddividing, after said plated films are formed, said laminate having saidplated films on said external electrode layers, along said second breaktrenches.
 20. The method as claimed in claim 19, wherein: said firstbreak trenches to be formed on the side of said second principal faceare formed at positions corresponding to said second break trenchesformed on the side of said first principal face and along said secondbreak trenches formed on the side of said first principal face; saidsecond break trenches to be formed on the side of said second principalface are formed at positions corresponding to said first break trenchesformed on the side of said first principal face and along said firstbreak trenches formed on the side of said first principal face; and saidlaminate is divided such that portions near said first break trenchesare cut away in a thickness direction of said laminate earlier thanportions near said second break trenches.
 21. The method as claimed inclaim 17, wherein: said internal electrode patterns include firstinternal electrode patterns, and second internal electrode patternsprovided so that said first internal electrode patterns and said secondinternal electrode patterns are alternately arranged in a laminatingdirection of said ceramic green sheets through said ceramic greensheets; and said external electrode patterns include first externalelectrode patterns electrically connected with said first internalelectrode patterns, and second external electrode patterns spaced fromsaid first external electrode patterns and electrically connected withsaid second internal electrode patterns.
 22. The method as claimed inclaim 17, wherein said first break trenches have a depth of from 20% to70% of a thickness of said laminate.